静止质量为mo的粒子以运动（c为真空中的光速)，则其动能为（）

A.0.25m0c2

B.0.18m0c2

C.0.36m0c2

D.1.25m0c2

A.0.25m0c2

B.0.18m0c2

C.0.36m0c2

D.1.25m0c2

A.0.25m0c2

B.0.18m0c2

C.0.36m0c2

D.1.25m0c2

A.0.18m0c2

B.0.25 m0c2

C.0.36m0c2

D.1.25 m0c2

A.0.18m0c2

B.0.25 m0c2

C.0.36m0c2

D.1.25 m0c2

A.0.18m0c2

B.0.25 m0c2

C.0.36m0c2

D.1.25 m0c2

如图3-19所示，一质量为m0的粒子以速率的运动，碰上一个质量为2m0的静止粒子,碰后质量为m0的粒子运动方向偏转了45° ,速率变为。求质量为2m0的粒子碰后的速率和运动方向。